使用maven搭建springboot项目，有以下几种方式：
1. http://start.spring.io/
在上面网站选填项目基本信息（如：项目类型、语言、Spring Boot版本等），以及需要导入的依赖，点击“Generate Project alt + enter”生成 Spring Boot 项目的 zip 文件，下载解压导入IDE即可（选择导入maven项目）
2. 手动创建 maven 项目
“Create a simple project”勾选不勾选都可以
2.1.1勾选“Create a simple project”
填写 group id，artifact id 等信息，点击“Finish”
创建好的目录结构如上图所示，可以根据需要修改 jdk 的版本。
生成的 pom.xml 文件内容如下：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.com.first</groupId>
<artifactId>myfSpringBoot</artifactId>
<version>0.0.1-SNAPSHOT</version>
</project>
2.1.2 不勾选“Create a simple project”
"next"-->
"Finish"-->
生成的pom.xml文件内容如下：
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.com.second</groupId>
<artifactId>mysSpringBoot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<packaging>jar</packaging>
<name>mysSpringBoot</name>
<url>http://maven.apache.org</url>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
</properties>
<dependencies>
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>3.8.1</version>
<scope>test</scope>
</dependency>
</dependencies>
</project>
2.2 修改 pom.xml 文件，引入 <parent> 元素
继承<parent>pom里面已经引入了 tomcat、jetty 等很多常用依赖
2.2.1引入“1.4.0.RELEASE”版本的<parent> 元素
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
<modelVersion>4.0.0</modelVersion>
<groupId>cn.com.first</groupId>
<artifactId>myfSpringBoot</artifactId>
<version>0.0.1-SNAPSHOT</version>
<parent>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-parent</artifactId>
<version>1.4.0.RELEASE</version>
<relativePath/> <!-- lookup parent from repository -->
</parent>
</project>没有添加任何依赖也可以build。在项目根目录打开cmd命令行执行: mvn package 对项目进行打包。
会自动下载一堆 http://maven.aliyun.com 的 jar 到 maven 仓库，这是因为我的 setting.xml 文件配置的远程仓库是 aliyun 的远程仓库。（如下图）
项目构建成功后，我们来看一下项目 target 目录下发生的变化：
2.2.2有时候新建的 springboot 空项目直接引入 <parent> 元素会报错：
解决方案如下，配置一个远程仓库，例如 ：spring-milestones
<repositories>
<repository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</repository>
</repositories>
<pluginRepositories>
<pluginRepository>
<id>spring-milestones</id>
<name>Spring Milestones</name>
<url>https://repo.spring.io/milestone</url>
<snapshots>
<enabled>false</enabled>
</snapshots>
</pluginRepository>
</pluginRepositories><repositories>是 jar 包库，<pluginRepositories>是插件库。
2.3 启动类（这时只是一个普通的 maven 项目）
package cn.com.second;
public class StartApplication{
public static void main(String[] args){
System.out.println( "Hello Spring Boot!" );
}
}启动StartApplication
2.4 启动 springboot 项目
package cn.com.second;
import org.springframework.boot.SpringApplication;
public class StartApplication{
public static void main(String[] args){
SpringApplication.run(StartApplication.class, args);//需要引入下面依赖
}
}<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-actuator</artifactId>
</dependency>2.4.1 添加 springboot 默认配置文件 application.properties
2.4.2. 然后启动项目仍然不会报错，现在 controller 里面添加一个 test 方法，如下图：
此时启动类上需要添加注解 @SpringBootApplication ， 否则项目启动时会报错
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.0.M3)
2018-06-15 14:55:11.159 INFO 15640 --- [ main] c.c.s.mysSpringBoot.StartApplication : Starting StartApplication on lkk-PC with PID 15640 (F:\workspace\mysSpringBoot\target\classes started by lkk in F:\workspace\mysSpringBoot)
2018-06-15 14:55:11.162 INFO 15640 --- [ main] c.c.s.mysSpringBoot.StartApplication : No active profile set, falling back to default profiles: default
2018-06-15 14:55:11.176 INFO 15640 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@527e5409: startup date [Fri Jun 15 14:55:11 CST 2018]; root of context hierarchy
2018-06-15 14:55:11.233 WARN 15640 --- [ main] ConfigServletWebServerApplicationContext : Exception encountered during context initialization - cancelling refresh attempt: org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
2018-06-15 14:55:11.238 WARN 15640 --- [ main] o.s.b.c.e.EventPublishingRunListener : Error calling ApplicationEventListener
java.lang.ClassCastException: org.springframework.boot.context.event.ApplicationFailedEvent cannot be cast to org.springframework.boot.web.context.WebServerInitializedEvent
at org.springframework.context.event.SimpleApplicationEventMulticaster.invokeListener(SimpleApplicationEventMulticaster.java:159) [spring-context-5.0.0.RC3.jar:5.0.0.RC3]
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:139) [spring-context-5.0.0.RC3.jar:5.0.0.RC3]
at org.springframework.context.event.SimpleApplicationEventMulticaster.multicastEvent(SimpleApplicationEventMulticaster.java:127) [spring-context-5.0.0.RC3.jar:5.0.0.RC3]
at org.springframework.boot.context.event.EventPublishingRunListener.finished(EventPublishingRunListener.java:114) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplicationRunListeners.callFinishedListener(SpringApplicationRunListeners.java:79) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplicationRunListeners.finished(SpringApplicationRunListeners.java:72) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.handleRunFailure(SpringApplication.java:803) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:338) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at cn.com.second.mysSpringBoot.StartApplication.main(StartApplication.java:9) [classes/:na]
2018-06-15 14:55:11.240 ERROR 15640 --- [ main] o.s.boot.SpringApplication : Application startup failed
org.springframework.context.ApplicationContextException: Unable to start web server; nested exception is org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:137) ~[spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-5.0.0.RC3.jar:5.0.0.RC3]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.refresh(ServletWebServerApplicationContext.java:122) ~[spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:750) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:386) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:327) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1245) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.SpringApplication.run(SpringApplication.java:1233) [spring-boot-2.0.0.M3.jar:2.0.0.M3]
at cn.com.second.mysSpringBoot.StartApplication.main(StartApplication.java:9) [classes/:na]
Caused by: org.springframework.context.ApplicationContextException: Unable to start ServletWebServerApplicationContext due to missing ServletWebServerFactory bean.
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.getWebServerFactory(ServletWebServerApplicationContext.java:186) ~[spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.createWebServer(ServletWebServerApplicationContext.java:160) ~[spring-boot-2.0.0.M3.jar:2.0.0.M3]
at org.springframework.boot.web.servlet.context.ServletWebServerApplicationContext.onRefresh(ServletWebServerApplicationContext.java:134) ~[spring-boot-2.0.0.M3.jar:2.0.0.M3]
... 8 common frames omittedt同时需要引入 web 依赖：
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-web</artifactId>
</dependency>顺利启动：
. ____ _ __ _ _
/\\ / ___'_ __ _ _(_)_ __ __ _ \ \ \ \
( ( )\___ | '_ | '_| | '_ \/ _` | \ \ \ \
\\/ ___)| |_)| | | | | || (_| | ) ) ) )
' |____| .__|_| |_|_| |_\__, | / / / /
=========|_|==============|___/=/_/_/_/
:: Spring Boot :: (v2.0.0.M3)
2018-06-15 15:06:10.509 INFO 14536 --- [ main] c.c.s.mysSpringBoot.StartApplication : Starting StartApplication on lkk-PC with PID 14536 (F:\workspace\mysSpringBoot\target\classes started by lkk in F:\workspace\mysSpringBoot)
2018-06-15 15:06:10.512 INFO 14536 --- [ main] c.c.s.mysSpringBoot.StartApplication : No active profile set, falling back to default profiles: default
2018-06-15 15:06:10.550 INFO 14536 --- [ main] ConfigServletWebServerApplicationContext : Refreshing org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@527e5409: startup date [Fri Jun 15 15:06:10 CST 2018]; root of context hierarchy
2018-06-15 15:06:11.655 INFO 14536 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat initialized with port(s): 8082 (http)
2018-06-15 15:06:11.667 INFO 14536 --- [ main] o.apache.catalina.core.StandardService : Starting service [Tomcat]
2018-06-15 15:06:11.668 INFO 14536 --- [ main] org.apache.catalina.core.StandardEngine : Starting Servlet Engine: Apache Tomcat/8.5.16
2018-06-15 15:06:11.767 INFO 14536 --- [ost-startStop-1] o.a.c.c.C.[Tomcat].[localhost].[/] : Initializing Spring embedded WebApplicationContext
2018-06-15 15:06:11.768 INFO 14536 --- [ost-startStop-1] o.s.web.context.ContextLoader : Root WebApplicationContext: initialization completed in 1220 ms
2018-06-15 15:06:11.937 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.ServletRegistrationBean : Mapping servlet: 'dispatcherServlet' to [/]
2018-06-15 15:06:11.941 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'metricsFilter' to: [/*]
2018-06-15 15:06:11.941 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'characterEncodingFilter' to: [/*]
2018-06-15 15:06:11.942 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'hiddenHttpMethodFilter' to: [/*]
2018-06-15 15:06:11.942 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'httpPutFormContentFilter' to: [/*]
2018-06-15 15:06:11.942 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'requestContextFilter' to: [/*]
2018-06-15 15:06:11.942 INFO 14536 --- [ost-startStop-1] o.s.b.w.servlet.FilterRegistrationBean : Mapping filter: 'webRequestLoggingFilter' to: [/*]
2018-06-15 15:06:12.289 INFO 14536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerAdapter : Looking for @ControllerAdvice: org.springframework.boot.web.servlet.context.AnnotationConfigServletWebServerApplicationContext@527e5409: startup date [Fri Jun 15 15:06:10 CST 2018]; root of context hierarchy
2018-06-15 15:06:12.357 INFO 14536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/test]}" onto public java.lang.String cn.com.second.mysSpringBoot.controller.SecondController.test()
2018-06-15 15:06:12.364 INFO 14536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error]}" onto public org.springframework.http.ResponseEntity<java.util.Map<java.lang.String, java.lang.Object>> org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.error(javax.servlet.http.HttpServletRequest)
2018-06-15 15:06:12.364 INFO 14536 --- [ main] s.w.s.m.m.a.RequestMappingHandlerMapping : Mapped "{[/error],produces=[text/html]}" onto public org.springframework.web.servlet.ModelAndView org.springframework.boot.autoconfigure.web.servlet.error.BasicErrorController.errorHtml(javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse)
2018-06-15 15:06:12.391 INFO 14536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/webjars/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-15 15:06:12.391 INFO 14536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-15 15:06:12.426 INFO 14536 --- [ main] o.s.w.s.handler.SimpleUrlHandlerMapping : Mapped URL path [/**/favicon.ico] onto handler of type [class org.springframework.web.servlet.resource.ResourceHttpRequestHandler]
2018-06-15 15:06:12.628 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/beans || /application/beans.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.630 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/loggers/{name:.*}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.LoggersMvcEndpoint.get(java.lang.String)
2018-06-15 15:06:12.631 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/loggers/{name:.*}],methods=[POST],consumes=[application/vnd.spring-boot.actuator.v2+json || application/json],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.LoggersMvcEndpoint.set(java.lang.String,java.util.Map<java.lang.String, java.lang.String>)
2018-06-15 15:06:12.631 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/loggers || /application/loggers.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.632 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/metrics/{name:.*}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.MetricsMvcEndpoint.value(java.lang.String)
2018-06-15 15:06:12.632 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/metrics || /application/metrics.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.633 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/auditevents || /application/auditevents.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public org.springframework.http.ResponseEntity<?> org.springframework.boot.actuate.endpoint.mvc.AuditEventsMvcEndpoint.findByPrincipalAndAfterAndType(java.lang.String,java.util.Date,java.lang.String)
2018-06-15 15:06:12.634 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/env/{name:.*}],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EnvironmentMvcEndpoint.value(java.lang.String)
2018-06-15 15:06:12.634 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/env || /application/env.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.635 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/autoconfig || /application/autoconfig.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.636 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/trace || /application/trace.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.637 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/health || /application/health.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.HealthMvcEndpoint.invoke(javax.servlet.http.HttpServletRequest,java.security.Principal)
2018-06-15 15:06:12.637 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/info || /application/info.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.638 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/mappings || /application/mappings.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.638 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/dump || /application/dump.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.639 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/configprops || /application/configprops.json],methods=[GET],produces=[application/vnd.spring-boot.actuator.v2+json || application/json]}" onto public java.lang.Object org.springframework.boot.actuate.endpoint.mvc.EndpointMvcAdapter.invoke()
2018-06-15 15:06:12.639 INFO 14536 --- [ main] o.s.b.a.e.mvc.EndpointHandlerMapping : Mapped "{[/application/heapdump || /application/heapdump.json],methods=[GET],produces=[application/octet-stream]}" onto public void org.springframework.boot.actuate.endpoint.mvc.HeapdumpMvcEndpoint.invoke(boolean,javax.servlet.http.HttpServletRequest,javax.servlet.http.HttpServletResponse) throws java.io.IOException,javax.servlet.ServletException
2018-06-15 15:06:12.722 INFO 14536 --- [ main] o.s.j.e.a.AnnotationMBeanExporter : Registering beans for JMX exposure on startup
2018-06-15 15:06:12.731 INFO 14536 --- [ main] o.s.c.support.DefaultLifecycleProcessor : Starting beans in phase 0
2018-06-15 15:06:12.818 INFO 14536 --- [ main] o.s.b.w.embedded.tomcat.TomcatWebServer : Tomcat started on port(s): 8082 (http)
2018-06-15 15:06:12.822 INFO 14536 --- [ main] c.c.s.mysSpringBoot.StartApplication : Started StartApplication in 2.563 seconds (JVM running for 2.82)
3. @ResponseBody 注解
访问2.4.2 中的test方法会404，解决方法有两种
① 此时需要在方法上加 @ResponseBody 注解
② 把 @Controller 注解换成 springboot 的注解 @RestController
@RestController 等同于@Controller 加上 @ResponseBody
4. 一个接口对应多个 url
